Electric light



Nov. 10, 1936. o. T. MCILVAINE 2 060,584

ELECTRIC LIGHT Filed July 16, 1930 2 Sheets-Sheet l Nov. 10, 1936. Q T. MclLVAlNE 2,060,584

ELECTRIC LIGHT Filed July 16, 1930 2 Sheets-Sheet 2 o'rjlyfimmr 2297817 DZ 5 MM? A iz'arngy Patented Nov. 10, 1936 UNITED STATES PATENT OFFICE ELECTRIC LIGHT Application July 16, 1930, Serial No. 468,316

8 Claims. (Cl. 176-1) This invention relates to electric lights and has for its broadest aspect the provision of means for preventing blackening of the bulb walls or at least of so directing and controlling the discharged particles as to cause certain areas of the glass to remain clear. This branch of the invention is applicable alike to filament lamps and to lamps which derive a part of their light from gas-arcs or positive column glow. Another aspect of my invention relates to an improved discharge type of bulb adapted to produce a mixture of all kinds of rays, viz: infra-red, visible, actinic, and ultra-violet, capable of afiording the physiological effects of sunlight and with a minimum of complication, expense, or servicing requirements and also with a minimum of apparatus such as transformers, coils and the like. Another object of the invention is the provision of a simple and inexpensive lamp which shall produce a very large amount of light. Another object of the invention is the production of a white light containing all wave lengths, and at a high efficiency ratio of light production to energy consumed. Another object of the invention is the provision of a simple and inexpensive lamp whereby heat rays, light rays, and ultraviolet rays can be produced in about the same proportions as exist in stronger sunlight. Further objects and advantages of the invention will be apparent as the description proceeds. This application is a continuation in part of my prior application Serial No. 425,455, filed February 3, 1930.

In the drawings accompanying and forming a part of this application I have shown a few specimen embodiments of my inventive idea. Fig. 1 is a vertical sectional view through a complete lamp containing my improvements but designed for rather low voltage; Fig. 2 is a sectional view drawn to a rather large scale showing the relation of the light-giving parts; Figs. 3 to 7 inclusive show modified arrangements of the lightgiving parts, the two last mentioned being arranged for 110 volt .operation without transformers; Fig. 8 illustrates certain of my shielding expedients as applied to an incandescent filament bulb so as to localize the blackening; Figs. 9 and 10 are horizontal sectional views corresponding to the lines 99 and 10-10 respectively of Figs. 1 and 3; Fig. 11 is a side elevation partly diagrammatic in character of another modified form of lamp bulb containing my improvements and Fig. 12 is a detail view of another arrangement of filaments and grids.

In the form shown in Figs. 1 to 7 and 9 to 12 my improved lamp combines the principle of filament operation and that of positive-column discharge illumination. In the form shown in Fig. 8, I show a filament lamp only. Each preferably comprises a bulb I having a neck 2 fitted 5 with a flange 3 provided with a tube 4 and press 5. Sealed in the press are leading-in wires 6 and 1 between which is connected the filament 8.

Carried by the two leading-in wires and facing each other are electrodes l 0I0 for the posio tive column discharge. These in the form shown in Figs. 1, 3, 9 and 10, are made of hollow helical coils of tungsten wire, the turns laid closely together, the interiors open and facing each other at some little distance depending upon the size of 15 the lamp but generally from one-fourth inch to about an inch. These coils are easily supported in place by having the terminals of the tungsten wire welded to the leading-in-wires as shown at l l in Fig. 3, and the parts thus far described are sufficient for the simplest type of lamp when the bulb is provided with a filling of easilyionizable gas such as argon, neon, helium, etc., at a pressure from 1 to 300 mm. of mercury and preferably between about 50 to mm. When 25 a current is applied to such a lamp the glowing filament soon ionizes the gas to the point where an independent discharge begins to take place between the electrodes l0l0 resulting in a great increase in the amount of light produced, this light also proving very rich in ultra-violet and actinic rays.

Preferably I also introduce into the bulb a small button "5 of mercury which has the properties of becoming volatilized as the temperature increases and increasing the-conductivity of the atmosphere, thereby increasing the intensity of the arc and the proportion of ultra-violet radiation. This useof mercury also renders the device much more efiicient as a producer of light, 40 the radiations emitted greatly increasing in intensity, and the E. M. F. decreasing, even with constant current flowing, for example from 15 volts down to 10 volts across the gap.

Of course it is also possible and within my invention to coat the interior of the electrodes with emission-facilitating material, such for example as alkali metals, thorium, caesium and other highly-emissive substances. However, I do not advocate this as I do not consider the advantage 50 worth the added expense, but I do advocate the employment of some means for controlling the amount of current either manually or automatically, since the discharge path by way of the electrodes as soon as the arc is established here, 5

ordinarily exhibits much lessresistance than the filament itself, so that an excessive current will be developed unless suitable precautions are taken. These precautions can consist of manually connecting the lamp through a higher resistance, or to a source of lower potential, as will be obvious, or by employing what is known as a constant-current transformer, an example of which is illustrated in Fig. 11. This consists essentially of a core element I I0 having a primary winding Ill connected to the supply mains, and a secondary winding I i2, generally of fewer turns than the primary, connected to the lamp. This transformer is characterized by the presence of a magnetic by-pass of some kind here indicated at H3 adapted to permit an increased amount of the magnetic lines produced by the primary to flow through this path as the flow of the same through the coils H2 is throttled by the increasing current in those coils. It will be understood that this drawing is essentially diagrammatic so far as this transformer is concerned and that the same may occur in a great many different specific forms.

Such an intense positive-column discharge always tends to produce what is known as sputtering of the electrodes with consequent blackening of the container-walls. This sputtering can be reduced to some extent by proper choice of the shape and material of the electrodes for example by making the same cup-shaped and hollow as shown at [2 in Figs. 4 and 5, the open mouth of the cups being presented towards each other. It is still better to make these electrodes of coiled tungsten wire, closely wound into helix form as shown at [2 in Fig. 3' since the mechanically treated and drawn wire has a greater density than other forms of the metal. In both forms of electrode the major portion of the discharge comes from the interior, thereby confining the sputtering to some extent and preventing or at least retarding the blackening of the bulb.

The very great intensity of the discharge however causes it to tend to overrun onto the exterior of these electrodes and to oppose and diminish this tendency I preferably surround each electrode with a spaced, insulated, wire coil 13, parallel and more or less accurately concentric there with, although the latter point is of comparatively small importance within wide limits. These coils are located with their axes pointing at those points of the container wall which are located in line with the electrodes and at the ends of the filament and hence of comparatively little value as regards light transmission. In Fig. l, I have shown these coils as sealed to a glass header l4 carried by the leading-in wires. In Fig. 5, I haveshown them as carried by a glass header l5 sealed in the press. The operation of these coils depends upon the fact that insulated metallic bodies of this nature, located inside such a container, tend to pick up stray electrons until a considerable charge is accumulated, and this charge exhibits the phenomena of repelling the cathode glow and causing it to confine itself inside the electrodes, at least throughout a much larger range of current-densities than otherwise, and of opposing a lateral throwing of electrons, while positively charged bodies are caught or deflected. This arrangement effectually retards the blackening of the bulb interior, especially the lateral portions.

This, however does not wholly stop the sputter'ing effect and blackening of the bulb will still occur if given sufficient time. I have therefore found it advantageous in some cases to deflect the electrodes and their surrounding coil somewhat towards one side of the container I as shown in Figs. 9 and 10, the result being to cause the ejected particles to collect chiefly on the portion of the bulb designated by the letter A, the remaining portions remaining substantially unaffected.

The form of the device shown in Figs. 1 to 5 inclusive is designed to run at less than volts, for example about 35 to 40 volts starting, and 15 to 20 volts running, at which potential it utilizes about 400 watts and affords a dazzling intensity of light. In Fig. 6, I have shown a modification to facilitate the use of the lamp on 110 volt circuit without special transformer. The press 5 carries a post 20 of insulating material from which project the spaced wires 2| carrying spaced electrodes 22 each f which is preferably a hollow cylinder of highly-resistant metal such as tungsten or other metal having a melting point above 2300 C.

These wires are also connected by filaments 23, and the terminal wires are connected one to each of the leading-in wires 6, I, and insulating tube 24 being preferably employed around one of these wires to prevent arcing. In the form of the invention shown in Fig. '7 each of the electrodes 22 is surrounded by a coil l3, wholly insulated from the electrode and from all other objects. The filament 23 in this illustration is formed in one piece which is connected between the leading-in wires 5 and l, the electrodes 22 being connected to separated points thereof by means of other filamentary wires 25. It seems to be important that these intermediate electrodes be connected to something in order to enable the leaking off.

of any collected potential. This can be done by providing any conductive path, for example by blackening the surface of the post 20 in gas flame or by sufficiently reducing the lead compounds contained in the glass, or by applying a thin metallic filament. Another mode is by connecting each of the intermediate electrodes to corresponding points of the filament either by the conductor leads 2i shown in Fig. 6 or by filament leads 25 as shown in Fig. 7. When gridcoils 53 are also employed as shown in Fig. 7 the post must, of course, be kept free from any conductive layer and the filaments 25 must be kept out of contact with the grid-coils, although no special care in setting is necessary since no arcing can occur to or from any grid-coil.

In Fig. 12, I have illustrated my improvements as applied to another form of device adapted for use with a comparatively high potential such as 110 volts. ried by one of the leading-in wires such as T and carries in its turn two metal posts 3l-3l which terminate in electrodes 32-32 of any suitable type. These electrodes are connected one with the other by means of a fine filament 8, and each with its corresponding leading-in wire by a heavier ballasting filament 33. When current is applied to this lamp the operation of the filament 8 ionizes the surrounding gas until an arc is started between the electrodes which are promptly raised to bright white heat of 3,000 to 5,000 F.,'while the arc itself may carry any temperature up to 6,000 or 7,000 F. I preferably employ a fairly high pressure of gas in these tubes for various reasons, one being that a low pressure are tends to fill the entire container whereas the high-pressure arc tends to become more localized. This high-pressure arc is guided or repelled away from undesired points by the control grids. The glass employed must be one which will stand pres- In this case a glass header 30 is carill) , sure at the temperature employed, and is preferably one which also is transparent to light waves down to a wave length of about 2300 Angstrom units. The pressure of the gas employed must hence be such that under the extreme high temq perature of operation will not burst the bulb, which means'ordinarily that it cannot be above about 300 or 400 millimeters of mercury to start with when cold, this at the high pressure of normal operation will bring it up to about atmospheric conditions. It is desirable that the bulb have a long neck for the purpose of condensing the mercury.

This however is reliable only so long as arcing along the filaments is prevented, since unless proper precautions are observed, the current is likely to jump from anywhere on one filament to some place on the opposite electrode or filament, but this is prevented by surrounding each of the filaments 33 with a loosely coiled helical wire 34, properly insulated from everything as by having its ends 35 sealed into the header 30. It will be understood that the coil 33 can be carried on to surround the electrodes 32-42 and thereby reduce the sputtering tendency.

For example the filament 8 in Fig. 12 may be such a filament as will not become unduly heated by having a difference of potential of 110 volts impressed upon its two ends. It need carry only a comparatively small current and hence may be of rather thin wire. Thus it is enough if this should carry 25 watts of energy, while the filament 33 may be of much larger size so as to carry for example 500 watts at a difierence of potential of 50 volts between their ends. With an atmosphere of neon, or neon and argon, or other easily ionized gases at a proper pressure (which may be anywhere from say 50 millimeters of mercury or less up to 700 millimeters of mercury or more) the potential across the arc may be adjusted to about 10 volts and the lamp becomes self governing without any special transformer or external resistance. I

The material of the container is chosen to allow the free passage of the rays produced, being preferably a glass of a type which will transmit light waves down to a wave length of about 2900 Angstrom units. It is necessary also to use'glass of rather high melting point since the amount of energy discharged from one of these bulbs is extremely great, the light produced being so dazzling as to simulate that of the sun. Each of these lamps is preferably made with a rather long neck 2 which being somewhat removed from In the form shown in Fig. 8 the filament 8 consists of a coil of fine wire which is itself coiled i the filament I secure a coil l3 of fine naked wire. Suppose now that the wire I be made positive either by connection to the side of a D. C. system or instantaneously by reason of A. C. alternations. The particles which cause blackening, in

case they be positive as I think they are, will be repelled by the coil l3 and will tend to be concentrated along the axis of the lamp, having the side walls unobscured for a much longer time. I.

This eflect can be augmented by placing a cross screen 40 across the other end of the lamp and connecting it to the negative terminal. I have also shown a second screen ll across the top of the bulb, connected by a spring coil 42 with the wire 1, thus permitting easy assembling. This may have some slight use with direct current in biasing the motion of particles toward the bottom of the lamp, but has its main use in an alternating current lamp by attracting and holding the particles during the reversals.

I do not assert that all blackening is avoided but that the useful lite of the bulbs is much increased, which is quite an item'with bulbs costing $5.00 to $10.00 each.

It will be understood that many changes in detail can be made without departure of the scope of my inventive idea and I do not limit myself to any of the details herein shown except as same are specifically recited in my several claims which I desire may be construed broadly, each independently of limitations contained in other claims.

Having thus described my invention what I claim is:

'1. Apparatus for producing electric light com-, prising a closed container which is transparent to the rays desired, a pair of leading-in wires sealed in the walls of said container, metallic electrodes connected one to each leading-in wire inside said container, each electrode comprising a hollow cylindrical body having a closed end, the closed end being connected to the leading-in wire and the open end being turned toward the other electrode, a readily ionizable gas at subatmospheric pressure in said container, and a hollow electrostatic shield surrounding each of said electrodes, and spaced therefrom and insulated from said electrodes and from the tube walls and substantially coaxial with said electrodes respectively.

2. An electric lamp comprising a closed container having therein an atmosphere of readily ionizable noble gases at a pressure between about 10 and 300 mm. of mercury in the cold, spaced metallic electrodes inside said container, leadingin wires connected to said electrodes respectively, a filament inside said container connected as a shunt from one electrode to the other, an insulated grid surrounding and spaced from those portions of the metallic elements inside said container from which the arc is desired to be deflected, and means for charging said grid so as to repel said arc, said container being of a material which is transparent to the radiations produced therein.

3. An electric lamp comprising a closed transparent container having therein an atmosphere of ionizable gas, a pair of leading-in wires sealed in the wall of said container, a filament inside said container connected between said leading-in wires and a series of three or more spaced metallic electrodes inside said container defining a positive-column discharge path in shunt relation with said filament, the terminal electrodes being connected to said leading-in wires by filaments adapted to limit the amount of current passing through said positive-column path, and means for discharging accumulated potential from an intermediate electrode.

4. An electric lamp comprising a closed transparent container having therein an atmosphere of ionizable gas, a pair of leading-in wires sealed in the wall of said container, a series of three or more spaced metallic electrodes inside said container and defining a plurality of positive column discharge paths arranged in series, the terminal electrodes being connected in conductve relation inside said container defining a positive-column discharge path in shunt relation with said filament, the terminal electrodes being connected to said leading-in wires by filaments adapted to limit the amount of current passing through said positive-column path.

6. An electric lamp comprising a closed transparent container having therein an atmosphere of ionizable gas, a pair of leading-in wires sealed in the wall of said container, a series of spaced metallic electrodes inside said container and defining a plurality of positive column discharge paths arranged in series, the terminal electrodes being connected in conductive relation to said leadingin wires, and means for discharging negative potential from said electrodes.

7. An electric lamp comprising a closed transparent container having therein an atmosphere of ionizable gas, an incandescible filament in said container, leading-in wires permanently connected to said filament, spaced electrodes in said container defining a positive-column discharge path in shunt relation to said filament, and high resistance conductors for connecting said electrodes to said leading-in wires and for limiting the amount of current passing through said positive-column path.

8. An electric lamp comprising a closed transparent container having therein an atmosphere of ionizable gas, an incandescible filament in said container, leading-in wires permanently connected to said filament, spaced electrodes in said container defining a positive-column discharge path in shunt relation to said filament, and incandescible filaments for connecting said electrodes to said leading-in wires and for limiting the amount of current passing through said positive-column path.

ORAN T. MCILVAINE. 

